Obama's bounce smaller than others

Barack Obama’s post-Democratic National Convention bounce in the polls appears to be slightly smaller than the norm of past conventions, and it's gradually depreciating.

The Gallup daily tracking poll has found that since the conclusion of the convention, Obama has risen 4 percentage points in the polls, to lead McCain 49 percent to 43 percent today. That's a slightly smaller uptick in the polls than the 5- to 6-point bounce earned by a typical party nominee, by Gallup’s measure, since 1964. Obama and McCain were evenly split at 45 percentage points apiece prior to the Democratic convention, according to Gallup.

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That outcome comes despite Obama’s speech before more than 80,000 people at Invesco Field in Denver on Thursday night, a political event that was also seen by about 40 million television viewers. It also comes as the Republican convention quietly got under way in St. Paul, and the national media gaze focuses southward to Hurricane Gustav.

Daily tracking polls by Gallup and Rasmussen Reports demonstrate that Obama has taken his greatest lead since July, if not the general election. But while Obama’s support remains significantly stronger than weeks ago, it appears that the post-convention bounce he earned may have already peaked.

On Saturday, Gallup reported Obama was ahead by 8 percentage points. By Monday, that lead had shrunk to 5 points. Rasmussen pegs Obama’s standing as relatively stable in recent days, with a 49 percent to 46 percent lead over McCain when “leaners” are included, a small but statistically insignificant improvement for McCain of 1 percentage point since Saturday.

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CBS News reported Monday that Obama is now ahead in its poll, 48 to 40 percent, a 3-point uptick in Obama’s standing compared to its poll prior to the Democratic convention. Obama’s 3-point bounce exceeds that of John F. Kerry, the Democratic presidential nominee in 2004 who did not rise in the polls following his convention. But Obama’s bounce is less than a third of what Al Gore received in 2000 and Bill Clinton received in 1992. Even Bob Dole, following the 1996 Republican convention, received a 4-point bounce in the polls, 1 point more than Obama.

But any Obama bounce, if it is sustained, could be said to be a victory for Democrats. In the days since Obama gave his address, the news cycles have been captured by the unveiling of Alaska Gov. Sarah Palin as John McCain's running mate, the opening of the Republican convention and the threat posed by Hurricane Gustav.

There have been only three previous back-to-back conventions, most recently in 1956. The effect of the GOP convention on the polls will not be known for days.

A CNN/Opinion Research Corp. poll and a Zogby Interactive flash poll, both completed over the weekend, have found the presidential race is in a dead heat. According to both polls, Obama attained no statistically significant convention bounce.

Whether Obama is ahead or tied with McCain, the presumptive Republican nominee will now come into the Republican convention with his best opportunity yet to break through his own ceiling and take a lead in the presidential race.